One of our major objectives involves the study of membranes of the epithelial cell of the small intestine using techniques developed in our laboratory which permit the isolation and separation of microvillus and lateral-basal membranes. We will examine the factors influencing the transport of nutrients, especially sugar and amino acids by membrane vesicles. We will also study the differences in uptake and translocation by the membranes from mature differentiated villus cells compared to undifferentiated crypt cells. Changes in membrane function in absorptive disorders such as gluten-induced enteropathy (sprue) will be investigated. Another related and major aspect of the research will focus on intestinal cell surface glycoproteins - their structure, biosynthesis and function. These studies will include continued investigation of the intestinal surface glycosyltransferases and their changes with intestinal cell turnover, differentiation and disease states.